Thread finger for shoe sewing machines



March 30, 1948.

THREAD FINGER FOR SHOE SEWING MACHINES Filed Oct. 25, 1946 F. ASHWORTH 2,438,491

Patented Mar. 30, 1948 THREAD FINGER FOR SHOE SEWING MACHINES Fred Ashworth, Wenham, Masse, assignor to United Shoe Machinery Corporation, Flemington, N. J a corporation of New Jersey Application October 25, 1946, Serial No. 705,595

3 Claims.- (01. 112-38) The present invention relates to lockstitch shoe sewing machines, the stitch forming devices of which comprise a curved hooked needle, alooper and a thread finger arranged to cooperate with the looper in laying the thread in the hook of the needle and pivotally mounted to swing within a slotted guide block at one side of the plane of the needle. As illustrated, the invention is embodied in a machine similar to that disclosed in United States Letters Patent No. 2,271,611, granted Februar 3, 1942, on application filed in the names of the present inventor and Carl F. Whitaker jointly, and No. 2,420,643,,granted May 20, 1947, on application Serial No. 588,821, filed April 17, 1945, in thename of the present inventor.

The object of the invention is to improve the operation of a sewing machine similar to that of the application to insure a uniform and accurate movement of the thread finger, particularly to prevent erratic movement as a result of looseness and wear within a slotted mounting block, by avoiding excessiveauncontrolled lateral movement of the thread finger within the mounting block. The thread finger is thereby enabled to move in a plane close to the path of the needle without the necessity of such extreme movement in the looper from one side of the plane of the needle to the other in laying the thread in the needle hook as would be required where uncontrolled lateral movement of the thread finger is possible. Thus, the movement of the looper may be reduced with consequent advantages in obtaining reliable needle looping in a certain and uniform manner and with the additional advan tages that the parts may be more easily adjusted and need not be manufactured with such a high degree of accuracy or under such close tolerances as has been necessary heretofore.

In the attainment of this object the thread finger of the present invention carries a lateral motion reducing shim adjustably secured to one side thereof between the side of the thread finger and the inner wall of the slotted block. Preferably the lateral motion adjusting shim is wedge shaped and is secured to an inclined surface of the thread finger so that the slot within the block may be conveniently formed with parallel inner walls.

These and other features of the invention as set forth in the appended claims will become apparent from the following description taken in connection with the accompanying drawings in which,

surrounding the sewing point of a shoe sewing machine in which the present invention isembodied;

Fig. 2 is-a detailview'in front elevation on an enlarged scale of the thread finger, work support and upper portion of the looper of the machine illustrated in Fig. 1;

Fig. 3' is a View in left side elevation of the same parts of the machine; and

Fig. 4 is an enlarged sectional view taken along the line IV-IV of Fig. 3.

The machine illustrated in the drawin s is a lockstitch: shoe outsole sewing machine having a work support 6, a presser foot 8, a curved awl Q, acurved hook needle Ill, a needle looper I 2, a thread finger M, a loop taker or shuttle iii, a take-up and other. stitch forming devices similar in: construction and mode of operation, exceptas hereinafter pointed out, to those disclosed in the patent and application above referred to.

Asin the machine'of the patent and application, thestitch forming devices are operated to cause a loop of thread to be laid in the book of the needle, to be pulled through the work by the needle, to be carried about a supply of looking threadby the loop. taker and to be drawn with an encircled portion of locking thread into the work to set each stitch. To lay the thread in the hook of. the needle the looper moves to'the left side of the plane of the needle where it engages the thread within: the hooked. upper end of the thread finger. Thethread' finger then moves rearwardly in a direction parallel to the plane of the needle and the looper moves from the'left side of the needle plane to the right side stretching the thread engaged with the thread finger and drawing it against the needle, so that as the needle is. retracted the thread will be carried securely into the needle hook. To reduce the motion of the looper as much as possible from one side of the needle plane to the other, the thread finger is located to move close to the needle path without actually interfering with the needle motion. The proximity of the thread finger to the needle path is limited only by the uncontrolled lateral movement of the thread finger which is determined by the accuracy with which the parts are fitted in assembling the machine. Frequently, as a result of faulty fitting or subsequent wear, it is necessary to adjust the thread finger so far from the plane of the needle that the thread will not be laid reliably within its hooked upper end. When this occurs the stitches inserted by the machine will be faulty Fig. 1 is a view in front elevation of a portion and irregular.

, curvature of the needle. Any looseness which appears in the pivotal mounting will be magnified, therefore, in unrestricted lateral movement of the upper hooked end of the thread finger. Ac-

cordingly, the thread finger must be located a sufficient distance from the plane of the needle to avoid possible contact with the needle as the needle penetrates the Work. correspondingly,

block 22 and the'thread finger are made.

greater movement from one side of the, plane of the needle to the other must be imparted to the looper in carrying the thread from the thread finger to the opposite side of the needle plane during looping perations.

To stiffen the mounting of the thread finger the slotted block of the present machine, as in the prior machine, provides bearings for a pin 24 clamped in position within the perforated lower end of the thread finger so that its ends project outwardly through the bearings in the portions of the block 22 forming the walls of the slot. The thread finger extends upwardly from the pivot pin 24 a substantial proportion of its length between the side walls of the slot in the block and is thus guided by the inner walls of the block to reduce the lateral motion at the upper endof the thread finger. In the construcreadilyto be taken up. To guide the shim along this surface the engaging surfaces of the shim and thread finger are provided with lengthwise mating tongue and groove formations, best shown in Fig. 4. After suitable adjustments havebeen made the shim is clamped securely in place by a setscrew 26 passing through a slot in the shim into threaded engagement with the thread finger. Preferably the shim is made of a softer material than that of which the pivot supporting For instance, with the usual steel construction beneficial results are obtained with the use of a bronze shim which has a tendency to wear more rapidly than the steel and, accordingly, may be replaced merely by removing the setscrew 26.

1 The nature and scope of the inventionhaving been indicated and an embodimentthereof having been specifically described, what is claimed is:

tion of the prior machine, with careful machining and fitting of the parts, accurate location of the upper end of the thread finger with relation to the needle and looper can be obtained, but after continued wear the thread finger must be replaced by one which will fit more accurately to the spacing between the inner walls of the slotted block.

To prevent excessive looseness of the thread finger in its mounting and to-avoid the necessity of extremely long side-to-side looper movements, the thread finger of the present invention is provided with a simple and effective lateral motion reducing device in the form of an adjustable wedge-shaped shim I8 secured to an inclined surface 20 at the opposite side of the thread finger from the needle within the slotted guide block indicated at 22. To enable the slot in the block to be formed conveniently with parallel inner walls, the wedge angle of the shim is made to supplement the inclination of the surface 20 of the thread finger. In this way the outer exposed surfaces of the thread finger and shim are maintained in parallel relation to fit the slot in the block.

Movement of the shim I8'of the present invention along the inclined surface of the thread finger enables looseness from improper fitting or wear between the thread finger and slotted block 1. A lockstitch outsole shoe sewing machine having a curved hook needle, a loop taker, a needle looper, a thread finger movable close to the needle path and arranged to cooperate with the looper in layin the thread in the hook, of the needle, and a slotted guide block at onev side of the plane of the needle within the. slot of which block the threadfinger is pivoted, in combination with a lateral motion reducing shim adjustably secured to one side of the thread finger between the finger and the inner wall of the slotted block. I

2. A lockstitch outsole shoe sewing machine having a curved hook needle,a loop taker, a needle looper, a thread finger movable close to the needle pathand arranged to cooperate with the looper in laying the thread in the hook of the needle, and a slotted guide block at one side of the plane of the needle within the slot of which block the thread finger is pivoted, in combination with a lateral motion reducing shim adjustably secured to the side of the thread finger opposite the needle path between the thread finger and the inner wall of the slotted block.

3. A lockstitch outsole shoe sewing machine having a curved hook needle, a loop taker ,a needle looper, a thread finger formed with an inclined side surface andrarranged to cooperate with the looper in laying the thread in the hack of the needle, and a slotted guide block atone side of the plane of curvature of the needle within the slot of which block the thread finger is pivoted, in combination with means for reducing the lateral motion of the thread finger comprising a wedge-shaped shim adjustably secured to a side of the thread finger and formed with an angle supplemental to the inclination of the inclined surface on the thread finger to bring the outer surfaces of the thread finger and shim into parallel relation fitting the slot in the block.

' FRED ASHWORTI-I. 

